Herbert Romulus O'Conor (November 17, 1896 – March 4, 1960) was an American lawyer serving as the 51st Governor of Maryland from 1939 to 1947.

His secretary, Camilla Conroy, died in the burning of the luxury liner SS Morro Castle in 1934.

O'Conor identified her body which was found floating face down close to the wreck site.

As governor, O'Conor created the Maryland Council of Defense during the Second World War.

In the Senate, O'Conor served as chairman of the Special Committee on Organized Crime in Interstate Commerce from May to September, 1951, during the Eighty-first Congress.